Print this page
Thursday, 24 February 2011 02:43

Safety and Ergonomics in Airframe Manufacturing

Written by
Rate this item
(0 votes)

Safety Management

The airframe manufacturing industry’s safety management systems have reflected the evolutionary process of safety management within the traditional manufacturing setting. The health and safety programmes tended to be highly structured, with the company executives directing health and safety programmes and a hierarchical structure reflective of the traditional command and control management system. The large aircraft and aerospace companies have staffs of safety and health professionals (industrial hygienists, health physicists, safety engineers, nurses, physicians and technicians) that work with line management to address the various safety risks that are found within their manufacturing processes. This approach to line control safety programmes, with the operational supervisor responsible for the daily management of risks, supported by a core group of safety and health professionals, was the primary model since the establishment of the industry. The introduction of detailed regulations in the early 1970s in the United States caused a shift to a greater reliance on the safety and health professionals, not only for programme development, but also implementation and evaluation. This shift was a result of the technical nature of standards that were not readily understood and translated into the manufacturing processes. As a result, many of the safety management systems changed to compliance-based systems rather than injury/illness prevention. The previously integrated line control safety management programmes lost some of their effectiveness when the complexity of regulations forced a greater reliance on the core safety and health professionals for all aspects of the safety programmes and took some of the responsibility and accountability away from line management.

With the increasing emphasis on total quality management throughout the world, the emphasis is again being placed back on the manufacturing shop floor. Airframe manufacturers are moving to programmes that incorporate safety as an integral component of a reliable manufacturing process. Compliance takes on a secondary role, in that it is believed that while focusing on a reliable process, injury/illness prevention will be a primary objective and the regulations or their intent will be satisfied in establishing a reliable process. The industry as a whole currently has some traditional programmes, procedural/engineered-based programmes and emerging applications of behaviour-based programmes. Regardless of the specific model, those demonstrating the greatest success in injury/illness prevention require three critical components: (1) visible commitment by both management and the employees, (2) a clearly stated expectation of outstanding performance in injury/illness prevention and (3) accountability and reward systems, based on both endpoint measures (such as injury/illness data) and process indicators (such as per cent safety behaviour) or other proactive prevention activities that have equal weighting with other critical organization goals. All of the above systems are leading to a positive safety culture, which is leadership driven, with extensive employee involvement in both the process design and process improvement efforts.

Physical Safety

A substantial number of potentially serious hazards can be encountered in the airframe manufacturing industry largely because of the sheer physical size and complexity of the products produced and the diverse and changing array of manufacturing and assembly processes utilized. Inadvertent or inadequately controlled exposure to these hazards can produce immediate, serious injuries.

Table 1. Aircraft and aerospace industry safety hazards.

Type of hazard Common examples Possible effects
Physical
Falling objects Rivet guns, bucking bars, fasteners, hand tools Contusions, head injuries
Moving equipment Trucks, tractors, bicycles, fork-lift vehicles, cranes Contusions, fractures, lacerations
Hazardous heights Ladders, scaffolding, aerostands, assembly jigs Multiple serious injuries, death
Sharp objects Knives, drill bits, router and saw blades Lacerations, puncture wounds
Moving machinery Lathes, punch presses, milling machines, metal shears Amputations, avulsions, crush injuries
Airborne fragments Drilling, sanding, sawing, reaming, grinding Ocular foreign bodies, corneal abrasions
Heated materials Heat-treated metals, welded surfaces, boiling rinses Burns, keloid formation, pigmentation changes
Hot metal, dross, slag Welding, flame cutting, foundry operations Serious skin, eye and ear burns
Electrical equipment Hand tools, cords, portable lights, junction boxes Contusions, strains, burns, death
Pressurized fluids Hydraulic systems, airless grease and spray guns Eye injuries, serious subcutaneous wounds
Altered air pressure Aircraft pressure testing, autoclaves, test chambers Ear, sinus and lung injuries, bends
Temperature extremes Hot metal working, foundries, cold metal fabrication work Heat exhaustion, frostbite
Loud noises Riveting, engine testing, high-speed drilling, drop hammers Temporary or permanent loss of hearing
Ionizing radiation Industrial radiography, accelerators, radiation research Sterility, cancer, radiation sickness, death
Non-ionizing radiation Welding, lasers, radar, microwave ovens, research work Corneal burns, cataracts, retinal burns, cancer
Walking/working surfaces Spilled lubricants, disarranged tools, hoses and cords Contusions, lacerations, strains, fractures
Ergonomic
Work in confined spaces Aircraft fuel cells, wings Oxygen deprivation, entrapment, narcosis, anxiety
Forceful exertions Lifting, carrying, tub skids, hand tools, wire shop Excess fatigue, musculoskeletal injuries, carpal tunnel syndrome
Vibration Riveting, sanding Musculoskeletal injuries, carpal tunnel syndrome
Human/machine interface Tooling, awkward posture assembly Musculoskeletal injuries
Repetitive motion Data entry, engineering design work, plastic lay up Carpal tunnel syndrome, musculoskeletal injuries

 Adapted from Dunphy and George 1983.

Immediate, direct trauma can result from dropped rivet bucking bars or other falling objects; tripping on irregular, slippery or littered work surfaces; falling from overhead crane catwalks, ladders, aerostands and major assembly jigs; touching ungrounded electrical equipment, heated metal objects and concentrated chemical solutions; contact with knives, drill bits and router blades; hair, hand or clothes entanglement or entrapment in milling machines, lathes and punch presses; flying chips, particles and slag from drilling, grinding and welding; and contusions and cuts from bumping against parts and components of the airframe during the manufacturing process.

The frequency and severity of injuries related to the physical safety hazards have been reduced as the industry’s safety processes have matured. The injuries and illnesses related to ergonomically related risks have mirrored the growing concern shared by all manufacturing and service-based industries.

Ergonomics

The airframe manufacturers have a long history in the use of human factors in developing critical systems on their product. The pilots’ flight deck has been one of the most extensively studied areas in product design history, as human factors engineers worked to optimize flight safety. Today, the fast-growing area of ergonomics as it pertains to injury/illness prevention is an extension of the original work done in human factors. The industry has processes that involve forceful exertions, awkward postures, repetitiveness, mechanical contact stress and vibration. These exposures can be exacerbated by work in confined areas such as wing interiors and fuel cells. To address these concerns, the industry is using ergonomists in product and process design, as well as “participatory ergonomics”, where cross-functional teams of manufacturing employees, supervision and tooling and facility designers are working together to reduce ergonomic risks in their processes.

In the airframe industry some of the key ergonomic concerns are the wire shops, which require many hand tools to strip or crimp and require strong grip forces. Most are being replaced by pneumatic tools that are suspended by balancers if they are heavy. Height-adjustable workstations to accommodate males and females provide options to sit or stand. Work has been organized into cells in which each worker performs a variety of tasks to reduce fatigue of any particular muscle group. In the winglines, another key area, padding of tooling, parts or workers is necessary to reduce mechanical contact stress in confined areas. Also in the wingline, height-adjustable work platforms are utilized instead of stepladders to minimize falls and place workers in neutral posture to drill or rivet. Riveters are still a major area of challenge, as they represent both a vibration and forceful exertion risk. To address this, low-recoil riveters and electromagnetic riveting are being introduced, but due both to some of the performance criteria of the products and also the practical limitations of these techniques in some aspects of the manufacturing process, they are not universal solutions.

With the introduction of composite materials both for weight and performance considerations, hand lay-up of composite material has also introduced potential ergonomic risks due to the extensive use of hands for forming, cutting and working the material. Additional tools with varying grip size, and some automated processes, are being introduced to reduce the risks. Also, adjustable tooling is being used to place the work in neutral posture positions. The assembly processes bring about an extensive number of awkward postures and manual handling challenges that are often addressed by the participatory ergonomics processes. Risk reductions are achieved by increased use of mechanical lifting devices where feasible, re-sequencing of work, as well as establishing other process improvements that typically not only address the ergonomic risks, but also improve productivity and product quality.

 

Back

Read 4585 times Last modified on Friday, 12 August 2011 15:24